a little trick I used when dogs or puppies like to play bite my hand, was I wiped rubbing alcohol or you can use to swabs for when they are going to wipe you down before the needle. I rubbed that all over my fingers and then let them have at it. They grabbed a couple of times and then must have figured I did not taste good, and stopped. They actually hate that alcohol on their tongue. It did not take them long to learn...